1. Field of the Invention
The present invention relates to a resist pattern forming apparatus and the resist pattern forming method for forming a resist pattern on the substrate such as semiconductor wafers and LCD substrates (glass substrates for liquid crystal displays) with developing the substrates after coating therewith, for example, a resist solution, and exposure.
2. Description of the Related Art
In a semiconductor apparatus fabrication process, photolithography technology is used. In the photolithography technology, a resist solution is coated on a substrate such as a semiconductor wafer (herein after referred to as a wafer). With a photo mask, the resist film is exposed and developed. As a result, a desired resist pattern is formed on the substrate.
The photolithography technology is performed by a pattern forming system of which an aligner is connected to a coating and developing apparatus. Taking the case when the wafers are processed as an example, the coating and developing apparatus is composed of a cassette stage, a transfer mechanism, a processing station and an interface station. The carrier stage loads and unloads a wafer carrier. The transfer mechanism conveys a wafer from a carrier placed on the carrier stage. The coating and developing apparatus is connected to the aligner.
The wafer is carried into a processing station with a wafer transfer mechanism. A resist film is formed thereon in a coating unit, after that the wafer is being exposed in an aligner. Then the wafer is brought back to the processing station, a developing process is performed in a developing unit and the wafer is returned to the cassette with the transfer mechanism. After that the wafer is transferred to an etching apparatus where the etching process is performed as a next step.
Incidentally the processing state of the resist film thickness, the exposing process, the developing process, and the etching process may not meet a target value because of a fluctuation in a temperature and a humidity and the like, and factors such as a condition of a surface of the wafer and an atmospheric pressure, even when the process is performed under a constant processing conditions.
Thus, conventionally a substrate is pulled out, for example, every time when a fixed number of the substrates are processed. The substrate is conveyed in an inspection unit disposed in an area separated from the coating and developing apparatus. In the inspection unit an inspection is performed on items such as, a thickness of the resist film formed on the wafer after the coating of the resist solution, a line width of a resist pattern after the developing process, an accuracy that a base pattern matches with the resist pattern, inconsistency on the developed surface and a defect on the development, a line width of an etched line after the etching and a defect on the surface after the etching process. A decision is made onto whether the processing condition of each portion is appropriate based on the inspection result. The processing state of the wafer that is sent to manufacture line is amended to approach the target value based on the decision.
However, since there is no standard value that determines the amendment, an augmenter of an amending operation of such processing condition, is to be determined by experience of an operator and the like obtained with trial and error. In addition, there is a plurality of parameters that are an object of the amendment. The operation is troublesome since the inspection has to be repeated many times with various processing conditions and amendment values. In addition, the operation becomes difficult to be performed when in an absence of an experienced operator.
Furthermore, conventionally the amendment of the processing conditions is performed with each of the plurality of units, coating unit, developing unit, aligner, etching apparatus. Thus the operator has to visit each of those units or apparatuses in order to amend the processing conditions thereof, causing the operation to be troublesome also from this point of view.